XD-2061 Add Redis sink module

 - Add Redis sink with the following options:
    - topic (a SpEL expression)
    - hostname, port and password
Given the way validation errors are reported, it's actually better to use the negative of this (with @AssertFalse).
Indeed, on a violation of property "foo", we write:
* foo: the message
So with the current approach, the user would get
```
* mutuallyExclusive: the 'topic'  ....
```
and 
```
* valid: one of 'topic' ...
```
which is hard to interpret.
(I know I've used it myself somewhere, but have come to realize what I explain above)